What are the four methods used for water quality testing?Group of answer choicesLight Refraction DevicesColorimetric TestingLab-tested SamplesBioluminescence RetractionSensory TestingDirect Reading Probes

The four methods used for water quality testing are:

1. Light Refraction Devices: This method uses a device that measures the degree of refraction of light passing through the water. The level of impurities in the water can affect the refraction of light, thus providing an indication of the water's quality.

2. Colorimetric Testing: This is a simple and quick method that involves adding a reagent to a water sample and observing the color change. The degree of color change can indicate the presence and concentration of certain contaminants in the water.

3. Lab-tested Samples: This is the most accurate method of water testing. Samples of water are collected and sent to a laboratory for detailed analysis. This method can identify a wide range of contaminants and provide precise measurements of their concentrations.

4. Direct Reading Probes: These are devices that are inserted directly into the water to provide real-time measurements of certain parameters, such as pH, temperature, dissolved oxygen, and conductivity. These probes can provide a quick and easy way to monitor water quality.

Please note that Sensory Testing and Bioluminescence Retraction are not standard methods for water quality testing.